To improve the ease of use of scanning systems, in particular digital copiers, it is desirable to automatically register scanned objects (e.g., a hard copy document) on the platen of the input scanner. To facilitate automated registration or positioning of an object, it is necessary to identify the position, shape and rotation angle of the object. Such a capability can enhance productivity by decreasing the time required for scanning documents and reduce the requirement for accurate presentation placed upon document feeding mechanisms.
The present invention is directed to a system intended to automatically determine the boundaries of an object within a scanned image. The present invention combines a number of graphics and image processing techniques into an automated system that provides productivity enhancement for digital copiers and scanning systems.
The present invention accomplishes these objectives by:
Heretofore, a number of patents and publications have disclosed image registration or the use of moments in pattern recognition, the relevant portions of which may be briefly summarized as follows:
U.S. Pat. No. 485,568 to Venable et al., issued Jan. 16, 1996, and hereby incorporated by reference, discloses a method and apparatus for representing a complex color raster image as a collection of objects in a structured image format--a hierarchical, device-independent format. A structured image document, generated using the techniques described by Venable, is a representation of data that may be rendered into a raster image. The data includes simple raster images as well as a hierarchical collection of sub-objects and raster processing operations. The possible data types for objects in the structured image include a raster image, text, graphics, image processing description, and files containing multiple image representations
U.S. Pat. No. 5,528,387 to Kelly et al., issued Jun. 18, 1996, teaches electronic image registration in a scanner. In particular, the edge data of a document is detected and skew angle calculated. The image is then rotated based upon the skew angle and nonimage areas are filled using an image generation feature.
U.S. Pat. No. 4,922,350 to Rombola et al., issued May 1, 1990, discloses a two-pass scanning apparatus for detecting the size and position of an original document on a scanner platen. Image signals captured on a first scan are employed to determine boundaries and a best-fit magnification so that the image may be fit to a recording sheet using image signals generated on a subsequent scanning pass.
U.S. 5,253,765 to Moorehead et al, issued Oct. 19, 1993, teaches a system for sorting randomly sized objects (e.g., mushrooms). Invariant moments are employed, utilizing the complete pixel information for all pixels within the border of a captured image, to extract information about the mushroom size and orientation.
U.S. Pat. No. 5,220,398 to Horn et al. teaches an analog VLSI microchip that uses moments to determine the position and orientation of an object in a scene.
In "Invariant Fitting of Planar Objects by Primitives," published in 1996 IEEE Proceedings of ICPR '96, pp. 508-512 Voss et al. teach a method of pattern recognition using primitives such as triangles, rectangles, circles ellipses, superquadratics, etc. The authors further describe a technique for describing the primitives using moments in a normalized manner; resulting in a decrease in the numerical effort.
In "MANAGING AND REPRESENTING IMAGE WORKFLOW IN PREPRESS APPLICATIONS", Technical Association of the Graphic Arts (TAGA) Vol. 1, 1995 Proceedings pp. 373-385, hereby incorporated by reference for its teachings, Venable et al. teach the use of structured images to manage prepress workflow.
In accordance with the present invention, there is provided an imaging apparatus, comprising:
In accordance with another aspect of the present invention, there is provided a method for processing an image including:
One aspect of the invention deals with a basic problem in digital image processing, that of identifying an object within a digitized image. The solution to this problem is leveraged to accurately control the placement of an object within a digital document. The techniques described herein enable a user to expediently scan a document or other object, automatically recognizing the shape of the document within the digitized image, and composing a digital document incorporating the object. The invention employs binary moments in the recognition of the object to provide a robust recognition method.
The techniques described above are advantageous because they improve the efficiency of a scanning process, reducing the need for accurate registration of the object on the platen of the image input device. In addition, the techniques allow for the automatic re-registration of the object image in an output document without user intervention.